Ref issue

List <VectorLine> lines;

VectorLine line= new VectorLine ("Line", new Vector2[12], null, 1.0f);
lines.Add (line);


foreach (VectorLine line in lines) {
	Vector.DestroyLine (ref line);
}


error:
Assets/MyScripts/MyLineMaker.cs(41,49): error CS1657: Cannot pass `line' as a ref or out argument because it is a `foreach iteration variable'